Project Summary/Abstract Development of Optimized Endectocide-treated Bird Feed Formulations for West Nile Virus Control STTR Phase I Application PIs: Brady Clapsaddle, TDA Research, Inc.; Dr. Brian Foy, Colorado State University West Nile Virus (WNV) is the leading cause of domestically acquired arboviral disease in the United States, resulting in significant disease and death every year in both humans and wildlife. WNV is spread by mosquitoes, principally Culex spp. The development and marketing of a WNV vaccine for humans remains highly uncertain, thus targeting the mosquito vector with insecticides will remain the most practical strategy to control WNV for the foreseeable future. These insecticide applications, however, are indiscriminant, use large quantities of insecticide, are limited to wealthier urban and semi-urban communities that can afford them, are frequently opposed due to toxicity concerns, and are often poorly targeted due to focus on nuisance mosquitoes. Thus, Colorado State University (CSU) and TDA Research, Inc. (TDA) propose to develop a novel, environmentally-safe strategy to minimize the transmission of WNV in the U.S. Our method does not use utilize insecticide spraying but is expected to effectively control localized WNV transmission by Culex spp. mosquitoes. Recently, researchers at CSU have demonstrated in the laboratory that the endectocidal drug ivermectin is highly active against the primary WNV vector in the western U.S, Culex tarsalis. Our method utilizes this exceptionally safe drug to make treated bird feed. Birds that serve as the primary blood meal source for Culex tarsalis will then ingest this treated feed at feeders strategically placed in WNV-transmission hotspots, and mosquitoes that bite these treated hosts will have a high probability of dying before they can transmit WNV, thus lowering the risk of WNV in a zone around the feeder. Our approach for this Phase I project will be to develop and test an environmentally stabilized (e.g., stable to sunlight, humidity, heat, etc.) drug formulation for production of the treated feed and treatment of local bird hosts. We will then demonstrate the feasibility of our approach by showing that the formulation is stable under harsh environmental conditions, and that the stabilized formulation is transferred to potential hosts and subsequently to mosquitoes. Collection of crucial field data will also be done to gather empirical evidence to be used to construct a model in Phase II, and we will also assess its cost-effectiveness compared to alternatives. The overall goal of the proposed project is to provide a simple and low-cost, but scientifically-validated tool to minimize local risk of WNV transmission in the U.S., with an initial focus on the Great Plains, the region with the highest incidence of disease. With proof-of-concept in hand (after Phase II), we would expand the strategy to control WNV and other zoonotic arboviruses in other regions of the U.S. and the world.